Well, it is very hard to find this easter egg, and you can only find it by using some kind of flying cheat or in a private server, using the EmuHacker.

You have to go to the doors of Grim Batol (unfinished instance at the moment). There, you will have to "fly" to reach the top of Grim Batol's mountain. There, at the top of the mountain, you will see a broken tent, with some wooden boxes, and near, a word in the floor that says "HELP"

Nice huh? :)